The present invention relates generally to devices for measuring elapsed time, and in particular to a time-interval meter for measuring extremely short time intervals.
Conventional time measurement circuits typically employ direct counting techniques or ratios of counts in frequency /period measurements. One such technique is to gate a digital counter on upon some event, and stop the counter upon the occurrence of a second event. The counter counts clock pulses between the two events, and consequently the measured time interval has an error of .+-. one count. For long time intervals measured by counting high-speed clock signals, the one-count error may be inconsequential. However, for short time intervals, for example, in the sub-microsecond range, the count error becomes significant. In the prior art, this problem is overcome by employing an extremely high-speed clock and associated highspeed counter circuits, with attendant added complexity and high cost.